Un ADL pour les Architectures Distribuées à Composants Hétérogènes

National audienceDans cet article, nous présentons un ADL pour les architectures à composants hétérogènes et distribuées, et son utilisation au moment du déploiement. Actuellement, il n'existe pas de solution générique pour déployer une architecture distribuée basée sur différents intergiciels. Pour répondre à cette problématique, nous proposons dans cet article une approche pour décrire une telle architecture et un support pour le déploiement. Notre solution s'appuie sur un langage de description d'architecture possédant des notions de dépendances verticales et horizontales. Un exemple simple est présenté pour illustrer notre langage et pour valider nos contributions

Quelle histoire de la sculpture au XXe siècle ?

Les livraisons de l’année 2002 confirment l’intérêt soutenu pour les études sur la sculpture. Du point de vue de la consolidation de la connaissance, on dispose désormais d’un beau catalogue raisonné de l’œuvre sculpté de Fenosa (1899-1988), protégé de Picasso et Cocteau, auteur de la Tempête pourchassée par le beau temps (1957) placée boulevard Saint-Jacques à Paris en 1978-1979 et du Monument à Pau Casals (1976-1977) érigé à Barcelone en 1982. Ses fantasmagories, son style qui évoque les st..

« A la rencontre de Ralf Marsault »

Issu d’une thèse d’ethnologie (sous la direction de Jean Arlaud, Paris 7), Résistance à l’effacement est un remarquable exemple de visual studies, croisant les champs de l’histoire de l’art et de l’anthropologie. Ancré sur un « terrain », l’étude des Wagenburgen (regroupements de véhicules habités) de Berlin (Waldemar et East Side Gallery essentiellement), focalisé sur une population (les Wagenburger : des punks et des travellers), à un moment historique (de la chute du Mur à 1996), l’ouvrage..

Mapping the dependency of crops on pollinators in Belgium

peer reviewe

High-force catch bonds between the <i>Staphylococcus aureus</i> surface protein SdrE and complement regulator factor H drive immune evasion

The invasive bacterial pathogen Staphylococcus aureus recruits the complement regulatory protein factor H (fH) to its surface to evade the human immune system. Here, we report the identification of an extremely high-force catch bond used by the S. aureus surface protein SdrE to efficiently capture fH under mechanical stress. We find that increasing the external force applied to the SdrE-fH complex prolongs the lifetime of the bond at an extraordinary high force, 1,400 pN, above which the bond lifetime decreases as an ordinary slip bond. This catch-bond behavior originates from a variation of the dock, lock and latch interaction, where the SdrE ligand binding domains undergo conformational changes under stress, enabling the formation of long-lived hydrogen bonds with fH. The binding mechanism dissected here represents a potential target for new therapeutics against multidrug-resistant S. aureus strains. © 2023, The Author(s)

Scratching the surface : bacterial cell envelopes at the nanoscale

The bacterial cell envelope is essential for viability, the environmental gatekeeper and first line of defense against external stresses. For most bacteria, the envelope biosynthesis is also the site of action of some of the most important groups of antibiotics. It is a complex, often multicomponent structure, able to withstand the internally generated turgor pressure. Thus, elucidating the architecture and dynamics of the cell envelope is important, to unravel not only the complexities of cell morphology and maintenance of integrity but also how interventions such as antibiotics lead to death. To address these questions requires the capacity to visualize the cell envelope in situ via high-spatial resolution approaches. In recent years, atomic force microscopy (AFM) has brought novel molecular insights into the assembly, dynamics, and functions of bacterial cell envelopes. The ultrafine resolution and physical sensitivity of the technique have revealed a wealth of ultrastructural features that are invisible to traditional optical microscopy techniques or imperceptible in their true physiological state by electron microscopy. Here, we discuss recent progress in our use of AFM imaging for understanding the architecture and dynamics of the bacterial envelope. We survey recent studies that demonstrate the power of the technique to observe isolated membranes and live cells at (sub)nanometer resolution and under physiological conditions and to track in vitro structural dynamics in response to growth or to drugs

Mechanostability of the Fibrinogen Bridge between Staphylococcal Surface Protein ClfA and Endothelial Cell Integrin αVβ3

Binding of the Staphylococcus aureus surface protein clumping factor A (ClfA) to endothelial cell integrin αVβ3 plays a crucial role during sepsis, by causing endothelial cell apoptosis and loss of barrier integrity. ClfA uses the blood plasma protein fibrinogen (Fg) to bind to αVβ3 but how this is achieved at the molecular level is not known. Here we investigate the mechanical strength of the three-component ClfA-Fg-αVβ3 interaction on living bacteria, by means of single-molecule experiments. We find that the ClfA-Fg-αVβ3 ternary complex is extremely stable, being able to sustain forces (∼800 pN) that are much stronger than those of classical bonds between integrins and the Arg-Gly-Asp (RGD) tripeptide sequence (∼100 pN). Adhesion forces between single bacteria and αVβ3 are strongly inhibited by an anti-αVβ3 antibody, the RGD peptide, and the cyclic RGD peptide cilengitide, showing that formation of the complex involves RGD-dependent binding sites and can be efficiently inhibited by αVβ3 blockers. Collectively, our experiments favor a binding mechanism involving the extraordinary elasticity of Fg. In the absence of mechanical stress, RGD572-574 sequences in the Aα chains mediate weak binding to αVβ3, whereas under high mechanical stress exposure of cryptic Aα chain RGD95-97 sequences leads to extremely strong binding to the integrin. Our results identify an unexpected and previously undescribed force-dependent binding mechanism between ClfA and αVβ3 on endothelial cells, which could represent a potential target to fight staphylococcal bloodstream infections